Wide temperature range alkali metal grease containing excess alkali metal hydroxide



United States Patent WIDE TEMPERATURE RANGE ALKALI METAL GREASECONTAINING EXCESS ALKALI METAL HYDROXIDE John P. Dilworth and Oney P.Puryear, Fishkill, N. Y., assignors to The Texas Company, New York, N.Y., a corporation of Delaware No Drawing. Application April 27, 1951,Serial No. 223,430

18 Claims. 01. 252-333 I This invention relates to ball and rollerbearing greases which are characterized by high dropping points andoutstanding performance over a wide temperature range. The novel alkalimetal greases of this invention are suitable for operation attemperatures as low as 20 F. and as high as 500 F. and upwards.

The novel wide temperature range greases of this in vention result fromelevated temperature digestion of a mixture comprising mineral oil,alkali metal soaps of a fatty material of prescribed composition, and acritical amount of excess alkali metal hydroxide. The crtical factors inthe production of the wide temperature range greases of this inventionare the critical quantity of excess alkali metal hydroxide presentduring the high temperature digestion, the composition of the fattymaterial from which the alkali metal soaps are formed, the temperatureand duration of the digestion.

The novel wide temperature range greaeses of this invention are preparedby digesting at a temperature of 480 to 550 F. for a period of 2 to 5hours a dehydrated reaction mixture comprising 15 to 25 per cent alkalimetal soaps of a fatty material having an iodine number of at least 90,60 to 80 per cent mineral oil and 1.3 to 2.3 per cent alkali metalhydroxide. After digestion at the prescribed temperature, the grease isstirred down to a temperature of about 200 F. at which temperature it isdrawn. Additives comprising 1 to per cent of the total greasecomposition may be added during the cooling of the grease after theelevated temperature diges-v tion. Additives comprising 1 to 10 per centof the total grease composition may be added during the cooling of thegrease after the elevated temperature digestion.

The alkali metal greases produced in this invention are characterized bydropping points over 500 F. and possess good low temperature torqueproperties so that they are properly classified as wide temperaturerange ball and roller bearing greases. The low temperature properties ofthe grease produced in accordance with this invention can be improved bymilling. An improvement of 10 F. in the low temperature propertiesresults from milling the drawn grease.

Accordingly, it is recommended that the greases of this invention bemilled if they are to be utilized in lubricacomposition prescribed inthis invention are buttery-type greases with dropping points over 500 F.The preparation of alkali metal greases characterized by the aforesaidproperties represents a significant advance in the art of grease making.

Patented July 17, 1956 "ice , the added petroleum mahogany sulfonatesalt amounts to about 0.25 to 4 per cent of the final calculated greasecomposition. The sodium petroleum mahogany sulfomate is added to thereaction mixture together with the parafiin base oil and is presentduring saponification and dehydration of the reaction mixture. Whennaphthene base oils, commonly known as pale oils, are employed,

it is not necessary to employ stabilizing agents such as petroleummahogany sulfonate salts since greases of high stability are preparedwithout the use of a stabilizing 7 agent.

The mineral oil content of the novel greases of this invention comprise60 to per cent of the total calculated grease composition.Advantageously, the mineral oil content comprises approximately 65 to 75per cent of the total grease composition.

Soap-forming materials possessing a substantial olefin content arerequired for the formation of the alkali metal greases of thisinvention. The soap-forming stock, which can be soap-forming fattyacids, fatty esters .or mixtures thereof, should possess an iodinenumber of at least and preferably between 90 and 130.

A particularly preferred soap-forming material comprises a mixture ofmenhaden oil and hydrogenated fish oil fatty acids, which latter arecommercially known as Snodotte acids. A 3 to 1 menhaden oil-Snodotteacid mixture having an iodine value of approximately has provenparticularly useful as a soap-forming stock.

Commercially available Snodotte acids have approximately the followingsoap composition:

. Other unsaturated soap-forming acids and esters having an iodinenumber higher than 90, such as castor oil, linoleic and linolenic acids,may also be useful in the preparation of greases of this invention.

The soap-forming material of this invention is employed in such amountsthat the alkali metal soap content of the final grease compositioncomprises approximately 15 to 25 per cent of the total greasecomposition. Ordinarily the soap content of the grease is within therange of 18 to 22 per cent.

As indicated previously, the concentration of excess alkali metalhydroxide present during the elevated temperature digestion is criticaland lies in a very small range. It is necessary to maintainconcentration of excess alkali between the ranges of 1.3 and 2.3 percent of the final calculated composition of the grease in order toproduce a high dropping point grease. If the excess alkali metalhydroxide concentration is below or above the prescribed range, there isa significant lowering of the dropping point of the product grease.

It has been discovered that the viscosity of the paraf finic mineral oildetermines what is the optimum amount of excess alkali metal hydroxideto be used. When more viscous parafiinic mineral oils, for example, SAEgrade 30 or 40, are employed in formulating the. grease, best resultsfrom the viewpoint of dropping point are obtained if the excess alkalimetal hydroxide concentration is in the range of 1.4 to 1.6 weight percent whereas with less viscous paratfinic mineral oils, such as SAEgrade 10 to 20 oils, optimum results from the viewpoint of productquality are obtained if the excess alkali metal hydroxide concentrationis in the range of 1.7 to 2.1 weight per cent. However, regardless ofthe viscosity of the paraffinic mineral oil employed, the. total amountof excess alkali metal hydroxide falls within the prescribed range of1.3 to 2.3 weight per cent of the final calculated grease composition.

The excess alkali. metal hydroxide may be added either in its entiretyprior to elevated temperature digestion of the grease mixture or in two.separate fractions, with the major fraction being introduced prior todigestion. and a minor fraction being added during the stirred coolingof the grease. The entire excess alkali metal hydroxide or the majorfraction thereof is added to the grease. mixture together with thestoichiometric quantity of alkali required to saponify the soap-forming.material. The split feed incorporation of the excess alkali metalhydroxide is the preferred procedure and' produces a grease having.superior high temperature properties. 'In the split feed addition.

of excess alkali, approximately 60 to 80 per cent of the total excessalkali metal hydroxide is added together with stoichiometric quantity ofalkali required for neutralization of the soap-forming material; theremaining 20 to 40 per cent of total excess alkali is added during thestirred cooling of the grease at. a temperature of about 300 F. Asaturated aqueous solution. of alkali metal hydroxide serves as themeans of introducing the excess alkali and the stoichiometric alkalirequired for saponification of the soap-forming material.

The novel greases of this invention may be prepared from all alkalimetal hydroxides and the resulting greases are characterized by widetemperature range properties. Sodium and lithium base greases possessexceptionally high dropping. points and good low temperature torqueproperties.

The temperature and duration of the digestion of the mineral oil,alkali. metal soaps and excesscaustic are also decisive in determiningthe quality ofthe grease. digestion must be effected at temperaturesbetween. 480

and 550 F. to produce greases characterized by dropping points over 500F. and good low temperature torque properties. A temperature between 500and 550 F. is particularly preferred for the digestion. periodof 2 /2 to5 hoursis prescribed-but digestion times of 3 to.4. hours have provenparticularly advantageous.

After. the elevated temperature digestion, the grease is cooledwithstirringto a. temperature of about 200 F. at which temperature it isdrawn. Itis important to stir the grease duriugthev cooling period toprevent it from becoming stiff during a phase change which occurs atabout 350 F. It has been discovered that cooling the grease kettle at arate of 50 to 60 F. per hour while the grease Various additives areblended into the. grease after the elevated temperature digestion. ofthe saponified. dehy- Thc A digestion r' drated mixture. For example,diphenylamine, an oxidation inhibitor, may be blended into the grease ata temperature of about 220 to 250 F. during the stirred cooling of thegrease. Aluminum stearate, which imparts water resistance, is added atabout 500 F. or at the end of elevated temperature digestion. Ordinarilythe final grease composition contains 0.5 to 3 weight per centdiphenylamine and 3 to 7' weight per cent aluminum stearate.

The saponification procedure employed in manufacturing the greases ofthis invention is effected at conventional conditions. The minerallubricating oil fraction and the soap-forming stock are heated withstirring to a temperature of approximately to 160 F. to effect gooddistribution of the reagents. If a paratfin base mineral oil isemployed, the stabilizing petroleum mahogany sulfonate salt is added tothe mixture at this time. At approximately F. all or a major portion ofaqueous solution of alkali metal hydroxide is added to the reactionmixture. In small scale preparations, a small amount ofsilicone-anti-foam agent may be added together with the caustic solutionto minimize foaming. The

saponification is effected at a temperature between. 150

and200 F. in a period of about one hour.

Dehydration of the saponified reaction mixture is effected at atemperature between about 290 and 350 F..

and ordinarily takes approximately 1 to 2 hours. The preferredtemperature range for dehydrating the saponified reaction mass is 300 to330 F.

The. manufacture of the novel greases of this invention is illustratedin,Examples 1 and 2; in Example 1 the grease is prepared with SAE grade30 paratfinic lubricating oil and the total excess alkali metalhydroxide content, about 1.5 per cent, is incorporated in the greasemixture together with the stoichiometric quantity of alkali required forsaponification; in Example ll, an SAE grade 20 paraffinic oil isemployed and the excess alkali metal hydroxide, which is about 1.9 percent, is added in two increments, the major portion being added withstoichiometric amount of alkali and the minor portion during the stirredcooling of the grease.

Example I A mixture of 18 lbs. of SAE grade 30 paratfinic minerallubricating oil. fraction, 1.8 lbs. of pale oil solution containing 30.5weight per cent sodium petroleum mahogany sulfonate, 11.6 lbs. of a 3:1mixture of menhaden oil- S'nodotte acids were charged to a fire-heatedkettle wherein they were heated to about a temperature of 150 F. and 6grams of methyl silicone (Dow Corning Antifoam A) were added; At 150" F.5.45 lbs. of. a 49.5 per cent solution of sodium hydroxide, and 7 lbs.of water were added to the reaction mixture. The added caustic comprisesthe stoichiometric amount required to saponify the soapformingconstituents and in addition 1.5 per cent excess sodium hydroxide. to'450 F. over a two-hour period with the resulting saponification anddehydration of. the mixture; at this.

temperature, 2116 lbs. of SAE grade 30 paratfinic lube oil were addedover a /2 hour period. The mixture was then raised to 550 F. in a 1%hour period and held at this temperature for approximately three hours.The reaction mixture. was then cooled with stirring to a tcmperature of500 F. during a period of about 1 hour whereupon 3.0 lbs. of aluminumstearate was then added over a /2 hour period. The reaction mixture wasthen stirred down to a temperature of 250 F. over a 2 /2 hour period atwhich temperature 0.6 lb. of diphenyl amine dissolved in SAE grade 30paratfinic lube oil was added. The reaction mixture was then=furtherstirred down to a temperature of 200- F. over a 1% hour period at whichtemperaturethe grease was drawn from the kettle and pumpedthrough three60-mesh screens into containers. The high temperature grease thus,prepared had the following calculated composition:

The reaction mixture was raised 3:1 menhaden oil-Snodotte acid soap c s20.2

Excess alkali in charge 1.7 Glycerin (from fat) 1.6 Parafl'inic mineraloil SAE 30 67.5 Aluminum stearate 5.0 Sodium petroleum mahoganysulfonate 3.0 Diphenylamine 1.0 D. C. Anti-foam A p. p. m 220 Theproperties of the sodium base grease thus prepared are as follows:

Appearance, dark brown, smooth, glossy, buttery.

Min. pene. after 102-103 Torque breakdown machine No. 1, 80-250 F.:

Timken bearing Grease on brg 74 Leakage Overall rating Good Federalbearing- Grease on brg 28 Leakage 0 Good Overall rating Example II I Amixture of 18 lbs. of SAE grade 20 paraffinic mineral lubricating oilfraction, 1.8 lbs. of pale oil solution containing 30.5 weight per centsodium petroleum mahogany sulfonate, 11.6 lbs. of a 3:1 mixture ofmenhaden oil-Snodotte acids were charged to a fire-heated kettle whereinthey were heated to about a temperature of 150 F. and 6 grams of methylsilicone (Dow Corning Anti-foam A) were added. At 150 F., 5.45 lbs. of a49.5 per cent solution of sodium hydroxide and 7 lbs. of wash water wereadded to the reaction mixture. The added caustic comprised thestoichiometric amount required to saponify the soap-forming constituentsand 80 per cent of the total 1.9 per cent excess sodium hydroxide. Thereaction mixture was raised to 450 F. over a two hour period with theresulting saponification and dehydration of the mixture; at thistemperature, 21.6 lbs. of SAE grade 20 parafiinic lube oil was addedover a V2 hour period. The mixture was then raised to 550 F. in a 1%hour period and held at this temperature for approxi mately three hours.The reaction mixture was then cooled with stirring to a temperature of500 F. during a period of about 1 hour whereupon 3.0 lbs. of aluminumstearate was then added over a /2 hour period. The reaction mixture isthen stirred down over a three hour period to a temperature of 300 F.whereupon 168 g. of 49.5% solution of sodium hydroxidethe remainingexcess sodium hydroxide-and 50 cc. of water were added. After thereaction mixture was stirred down during a 45 minute period to atemperature of 250 F., 0.6 lbs. of diphenylamine dissolved in 1.08 lbs.of 20 grade paraffinic oil was added. After the reaction mixture hadbeen further cooled with stirring over a 1% hour period to 200 F., thegrease was drawn and pumped through three 60 mesh screens intocontainers. The grease thus prepared had the following calculationcomposition:

Na 3:1 menhaden oil-Snodotte acid soap 20.2 Excess alkali in charge 1.6

Added later 0.3- Glycerin 1.6 Parafiinic mineral oil SAE 20 67.4Aluminum stearate 5 .0 Sodium petroleum mahogany sulfonate 3.0Diphenylamine 1.0 D. C. Anti-foam A p. p. m 220 The properties of thesodium base grease thus prepared are as follows:

Appearance, brown, smooth, glossy, buttery.

Dropping point, "F 500+ Unworked pene 305 Worked pene 286 Low Temp.Torque, see./rev. atcw. cew.

0 F 1.8 1 6 -10 F 5. 0 4 2 -20 F 19 17 3o F 72 47 40 F 120 120 NormaHofiman oxidation, lb./ drop in 500 hr 17-17 Dynamic water resistance,per cent loss 10-17 Torque breakdown machine No. 1, -250 F.:

The foregoing examples illustrate the excellent wide temperature rangeball and roller bearing alkali metal greases of this invention. The highdropping points and the good low temperature torque properties areparticularly significant. The wide temperature range ball and rollerbearing alkali metal greases of this invention find a wide variety ofuses because of their excellent properties.

Obviously, many modifications and variations of the invention, ashereinbefore set forth, may be made without departing from the spiritand scope thereof, and therefore, only such limitations should beimposed as are indicated in the appended claims.

We claim:

1. A wide temperature range ball and roller bearing grease characterizedby high dropping point and good low temperature torque propertiescomprising a mixture of 15 to 25 per cent alkali metal soaps of asoap-forming material having an iodine number of at least 90, 60 to 80per cent mineral oil, 1.3 to 2.3 per cent alkali metal hydroxide, saidgrease having been prepared by incorporating said soap-forming materialin said mineral oil, adding to said mixture an amount of alkali metalhydroxide equivalent to the sum of the stoichiometric quantity requiredfor saponification plus the prescribed excess alkali metal hydroxide,saponifying said mixture,.

ture of menhaden oil and hydrogenated fish oil fatty.

acids, 60 to 80 per cent mineral oil, and 1.3 to 2.3 per cent alkalimetal hydroxide, said grease having been prepared by incorporating saidsoap-forming material in said mineral oil, adding to said mixture anamount of alkali' metal hydroxide equivalent to the sum of thestoichiometric quantity required for saponification plus the prescribedexcess alkali metal hydroxide, saponifying; said mixture, raisingsaidmixtureto a temperature of 480 to 550 R, digestingthe mixture atatemperature between 480 and -50- F. for 2 /2 to 5- hours, cooling saiddigested mixture with stirring toatemperature of about 200 F., anddrawingsaid grease about 200 F.

3. A grease according toclaim 2 wherein sodium soaps are employed;

4. A wide temperature range ball and roller bearing grease characterizedby high dropping point and good low temperature torque propertiescomprising a mixture of 15 to 25 per cent alkali metal soaps of asoap-forming material having an iodine number between 90 and 130, 60 to80 per cent parafiinic. mineral. oil, 0.25 to 4 per cent petroleum.mahogany sultonate salt, l.3 to. 2.3 per cent alkali metal hydroxide and1 to per cent additives, said grease having been prepared byincorporating said soap-forming material in said mineral oil, adding tosaid mixture an amount of alkali metal hydroxide equivalent to the sumof the stoichiometric quantity required for saponification plus theprescribed excess alkali metal hydroxide, saponifying said mixture,raising said mixture. to a temperature of 480 to 550 F., digesting themixture at a temperature between 480 and 550 F. for 2 /2 to 5 hours,cooling said digested mixture with stirring to a temperature ofabout 200F., incorporating said additives in said grease after said elevatedtemperature digestion while the grease is being stirred down to atemperature of about 200 F. and drawing said grease about 200 F.

5. A grease. according to claim 4 wherein. the soap formingmaterialcomprises a 3 to 1 mixture of menhaden oil and hydrogenated fish oilfatty acids.

6. A grease according to claim 4' wherein the additives arediphenylamine and aluminum stearate.

7. A grease according to claim 4 in which the paraffinic mineral oil isat lease SAE grade 30 and the excess alkali metal hydroxide is in therange of 1.4- to 1.7 weight per cent.

8'. A wide temperature range ball and roller bearing greasecharacterized by high dropping point and good low temperature torqueproperties comprising a mixture of to- 25 per cent alkali metal soaps ofa soap-forming material having an iodine number between 90 and 130, 60to 80-per cent paraffinic mineral oil, 0.25 to 4 per cent petroleummahogany sult'onate salt, 1.3 to 2.3 per cent alkali metal hydroxide,and l to 10 per cent additives, said ,grease having been prepared byincorporating said soapforming material in said mineral oil, adding tosaid mixture an amount ofalkali metal hydroxide equivalent to the sum ofthe stoichiometric quantity required for saponificationplus 60 to 80 percent prescribed excess alkali metal hydroxide, saponifying said mixture,raising said mixture to-a temperature of'480 to 550 F., digestingmixture at a temperature between 480 and 550 F. for 2V2 to 5 hours,cooling said grease mixture with stirring, adding to 40' per cent ofsaid excess alkali metal hydroxide at a temperature of about 300 F.,stirring said grease down to a temperature of about 200 F.,incorporating said additives in said grease after said elevatedtemperature digestion while the grease is stirred down to a temperature.of about 200 F., and drawing said grease, about 200 F.

9'. A grease, according to claim 8 wherein the additives arediphenylamine and aluminum stearate.

10. A grease according to claim 8 in which the soapforming materialcomprises a 3 to 1 mixture of menhaden oil andhydrogenated fish oilfatty acids.

ll. A grease according to claim'8 in which the parafiinic mineral oil isbelow about SAE grade 20 and the alkali metal hydroxide, content is inthe range of 1.7 to 2.1.

12. A grease comprising a wide temperature range ball and roller bearinggrease characterized'by high dropping point and good low temperatureproperties comprising a mixture of 15 to per cent sodium soaps of 3 to-1 mixture of menhaden oil and hydrogenated fish oil fatty acids,saidmixture having an iodine number of about 110; 60 to 80 per centparafiinic mineral oil, 0.25 to 4 per cent sodiumpetroleum mahoganysulfonate salt, 1.3- to- 2.3 per centsodium hydroxide, 3 to- 7 per centaluminum stearate and 0.5 to 3 per cent diphenylamine, said greasehaving been prepared by incorporating said menhaden oil-hydrogenatedfish oil fatty acid mixture in said paraffinic oil, adding to saidmixture an amount of sodium hydroxide equivalent to the sum of thestoichiometric quantity required for saponification plus 60 to 80 percent of the excess sodium hydroxide, saponifying said mixture, raisingsaid mixture to a temperature of 480 to 550 F., digesting the mixture ata temperature between 480 and 550 F. for a period of 3 to 4 hours,cooling said grease mixture with stirring, adding 20 to 40 per cent ofsaid excess sodium hydroxide during said stirred cooling at atemperature of about 300' F., incorporatingsaid diphenylamine andaluminum stearatc in said grease after elevated temperature digestion.during the stirred cooling and drawing said grease after it has beenstirred down to a temperature of about 200 F.

13. A grease according to claim 12 in which parafiinic mineral oil isSAE grade and the excess sodium hydroxide is about 1.5 weight per cent.

14. A grease according to claim 12 in which the parafiinic mineral oilis SAE grade 20 and the excess sodiumhydroxide is about L9 per cent.

15. A grease according to claim 12 in which the drawn grease is milledwith a resulting 10 F. improvement in its low temperature torqueproperties.

16. A process for preparing alkali metal greases characterized by highdropping point and good low temperature torque properties whichcomprises digesting at an elevated temperature of 480 to 550 F. for aperiod of 2 /2 to 5 hours a saponified dehydrated mixture comprising 15to 25 per cent alkali metal soaps of a soap-forming material having aniodine number of at least 90, 60 to 80 per cent mineral oil and 1.3 to2.3 per cent excess alkali metal hydroxide, cooling said digestedmixture with stirring to a temperature of about 200 F. and drawing saidgrease.

17. A process for preparing wide temperature range ball and rollerbearing greases characterized by high dropping point and good lowtemperature torque properties and comprising 15 to 25 per cent alkalimetal soaps of a. soap-forming material having an iodine number between90 and 130, 60 to 80 per cent mineral oil and 1*.3 to 2.3 per centexcess alkali metal hydroxide which comprises adding to a mixture ofsaid soap-forming material and said mineral oil an amount of alkalimetal hydroxide equivalent to the sum of the stoichiometric quantityrequired for saponification plus 60 to 80 per cent of the prescribedexcess alkali metal hydroxide, saponifying and dehydrating said mixture,digesting said dehy dratedmixture at a temperature of 480 to 550 F. fora period of 2 /1 to 5 hours, cooling said grease with stirring to atemperature of about 300 F., whereat the residual. 20 to per cent ofsaid alkali metal hydroxide is added, cooling said grease with stirringto a temperature of about 200 F. and drawing said grease.

18. A process for preparing alkali metal greases characterized by highdropping point and good low temperature torque properties whichcomprises digesting at an elevated: temperature of 480 to 550 F. for aperiod of 2% to 5 hours a saponified dehydrated mixture comprising 15 to25' per cent alkali metal soaps of a 3 to 1 mixture of menhaden oil andhydrogenated fish oil fatty acids. to per cent mineral oil and 1.3 to2.3 per cent excess alkali metal hydroxide, cooling said digestedmixture with stirring to a temperature of about 200 F. and drawing saidgrease.

(References on following page) References Cited in the file of thispatent UNITED STATES PATENTS Zimmer et a1. Dec. 9, 1941 Woods June 13,1944 5 Morgan Oct. 16, 1945 Zimmer et a1 Dec. 18, 1945 Liehe Feb. 12,1946 10 Beerbower Nov. 25, 1947 Morway et a1 Apr. 26, 1949 Butcosk Jan.24, 1950 Rudel Apr. 11, 1950 Morway July 4, 1950 Puryear et a1. Feb. 20,1951 Morway et a1 Apr. 29, 1952

1. A WIDE TEMPERATURE RANGE BALL AND ROLLER BEARING GREASE CHARACTERIZEDBY HIGH DROPPING POINT AND GOOD LOW TEMPERATURE TORQUE PROPERTIESCOMPRISING A MIXTURE OF 15 TO 25 PER CENT ALKALI METAL SOAPS OF ASOAP-FORMING MATERIAL HAVING AN IODINE NUMBER OF AT LEAST 90, 60 TO 80PER CENT MINERAL OIL, 1.3 TO 2.3 PER CENT ALKALI METAL HYDROXIDE, SAIDGREASE HAVING BEEN PREPARED BY INCORPORATING SAID SOAP-FORMING MATERIALIN SAID MINERAL OIL, ADDING TO SAID MIXTURE AN AMOUNT OF ALKALI METALHYDROXIDE EQUIVALENT TO THE SUM OF THE STOICHIOMETRIC QUANTITY REQUIREDFOR SAPONIFICATION PLUS THE PRESCRIBED EXCESS ALKALI METAL HYDROXIDE,SAPONIFYING SAID MIXTURE, RAISING SAID MIXTURE TO A TEMPERATURE OF 480TO 550* F., DIGESTING THE MIXTURE AT A TEMPERATURE BETWEEN 480 AND 550*F. FOR 2 1/2 TO 5 HOURS, COOLING SAID DIGESTED MIXTURE WITH STIRRING TOA TEMPERATURE OF ABOUT 200* F. AND DRAWING SAID GREASE.